Cowanw, I believe there is no difference in the final result, whether you use 00 or 1, with a 4 or a 5, when split-printing, except for the inability to reach the extreme grade of 00 or 5 if those filters are not used. The difference, however, is in the seemingly illogical relationship of the midtones affected by the discontinuity in the emulsion overlap, and the remaining tones, when moving from grade 00 to 0 and onwards. To put it in other words, as you move up a grade, from 00 to 0, and then towards 1, some midtones will immediately print denser at 00, than they would at 0, before they resume their march towards increased density at higher grades. I think this is what leads to a "solarised" look, that Bob Carnie mentioned when describing his 00 experience, see post 43 of this LFPP thread. You can see this in the two jumps of the 00 and 0 grade curves, which I have, rather poorly, plotted belowódisregard my error of a non-speed matched system, which lead to the curves not intersecting, as they should, at 0.60 logD. Notice the overall shape, and those almost 1 f/stop jumps, of the 00 curve:
Originally Posted by cowanw
Ilford MGIV WT 500H Curves (not to be trusted).png
Thank you, Steve, for correcting me.
Originally Posted by Steve Smith